// global objects
const a: Array<number> = [1,2,3]
const date = new Date()
date.getTime()
const reg = /^abc$/
reg.test('abc')

// build-in object
Math.pow(2,2)

// DOM and BOM
let body = document.body
let allLis =document.querySelectorAll('li')
allLis.keys()

document.addEventListener('click',e=>{
    e.preventDefault()
})

// Utility Types
interface IPerson {
    name: string
    age: number
}

let demonlb: IPerson = {
    name:'lb',
    age:20
}
type IPartial = Partial<IPerson>
let demonlb2: IPartial = {}

type IOmit = Omit<IPerson,'name'>
let demonlb3:IOmit= {age:20}